Objective To investigate the effects of hypoxia induced by CoCl₂ on the expression of adiponectin (ADPN) in mouse 3T3-L1 adipocytes. Methods 3T3-L1 preadipocytes were cultured and differentiated to matured adipocytes in vitro. Cell differentiation and lipid accumulation were determined by oil red O staining. CoCl₂ was used as a chemical hypoxia-inducible reagent to simulate hypoxic microenvironment. The expressions of hypoxia-inducible factor-1α (HIF-1α) and ADPN mRNA were detected by Real-Time PCR. The protein expressions of HIF-1α were determined by Western blotting and the secretion levels of ADPN protein in cell culture supernatant were detected by ELISA. Results Under the hypoxia condition induced by CoCl₂, the expression levels of HIF-1α mRNA and protein in 3T3-L1 adipocytes were significantly increased, while the expressions of ADPN mRNA in 3T3-L1 adipocytes and the secretion levels of ADPN protein in cell culture supernatant were significantly decreased. The expression levels of HIF-1α mRNA and ADPN mRNA had significantly negative correlation (r=－0.854, P<0.001). Conclusion The hypoxia induced by CoCl2 can decrease the expression of ADPN in 3T3-L1 adipocytes. This effect may be relevant to the metabolic function impairment of adipose cells and insulin resistance.